The present proposal concerns the detailed kinetic analyses of recombination in synchronous populations of cells engaged in meiotic or mitotic division. Special attention will be given to refining methods to be used for collecting synchronous populations of zygotes. Since zygotes may be committed to either the budding cycle or a sporulative cycle, by simple experimental treatments, the possibility of analyzing the consequences of any treatment, given to one parent, in the next division is especially promising. Kinetic analysis of cells entering into, but failing to commit to meiosis will represent a high priority item in the program. Correlated studies of macromolecular synthesis (DNA, RNA and Protein) should permit a critical resolution of the differences in recombination mechanism operative in zygotes as they enter into meiotic and mitotic cycles. Further characterization of mutants affecting recombination will be undertaken and new methods for isolating mutants deficient in reciprocal recombination will be developed.